The goal of this study is to develop a novel electrochemical S-nitrosothiol (RSNO) sensor with a better detection limit, and to determine the specifications required to build a practical RSNO analyzer for clinical diagnostic applications using this new electrochemical sensor as the detector. RSNOs are the carrier and reservoir of NO in vivo and may be a potential marker for endothelial dysfunction, thrombotic risk and inflammation. However, the clinical significance of endogenous RSNOs cannot be investigated without a quick and convenient assay for RSNOs. Compared to existing RSNO assay techniques, the proposed electrochemical RSNO sensor is highly sensitive and selective and is capable of measuring RSNOs in blood without any separation of pretreatments. A novel catalytic membrane will be prepared by covalently modifying cellulose dialysis membranes with selenocystamine to enhance the sensitivity of RSNO sensor. The design parameters, including appropriate blood dilution ratios, light protection, temperature control, sensor/reagent stability and the tolerance to varying levels of blood components (e.g., hematocrit/hemoglobin) will be determined and will serve as the criteria to build the first prototype RSNO analyzer in Phase II. PUBLIC HEALTH RELEVANCE: The goal in this grant is to develop a novel electrochemical S-nitrosothiol (RSNO) sensor with enhanced limit of detection, and to determine the specifications to use this RSNO sensor as the detector to build a practical RSNO analyzer for clinical diagnostic applications. Currently there is no quick and convenient technique to measure endogenous RSNO concentrations reliably.